Data Exfiltration: Sneaky New Ways Hackers Are Stealing Your Data

Data exfiltration refers to the unauthorized transfer of sensitive information from a target’s computer network to an external destination controlled by a malicious actor. As cyber defenses improve, hackers are coming up with creative new techniques to stealthily steal data without detection. In this article, I will provide an in-depth look at some of the latest data exfiltration methods being used by cybercriminals today.

Old School Exfiltration Techniques

Before diving into the new techniques, let’s briefly review some of the more traditional data exfiltration methods:

FTP

One of the earliest methods of data exfiltration involved using the File Transfer Protocol (FTP) to send files from the victim’s network to an external server controlled by the attacker. This is effective but relatively noisy as it generates significant network traffic.

DNS Tunneling

With DNS tunneling, data is encoded into DNS queries and sent to an external DNS server controlled by the hacker. The encoded data is then extracted and reassembled by the attacker. This technique is stealthier than FTP exfiltration.

Web Proxies

Data can also be exfiltrated through web proxies on the victim’s network. The proxy is configured to forward sensitive data to the attacker’s server.

Email Exfiltration

Data is embedded into image files or documents and emailed as attachments to accounts controlled by the attacker for later extraction.

While these techniques are still used today, advanced detection methods have made them riskier for attackers. This has led to the development of more covert exfiltration methods.

Sneaky New Techniques

Modern data exfiltration tradecraft focuses on stealth, misdirection, and concealment to avoid detection. Here are some of the latest tactics:

HTTPS Data Smuggling

With HTTPS data smuggling, the data is encoded into HTTPS requests sent to an external web server. This conceals the unauthorized transfer within normal encrypted web traffic.

DNSExfiltrator

DNSExfiltrator is an open-source tool that breaks exfiltrated data into small chunks and encodes it into DNS TXT record requests sent to an attacker-controlled domain. The data chunks are reassembled server-side.

Social Media Exfiltration

Sensitive files or data can be concealed inside images or videos and posted to a hacker-controlled social media account. This hides the exfiltration in normal user traffic.

Cloud Storage Exfiltration

With compromised cloud storage credentials, hackers can secretly transfer data into cloud accounts under their control. The cloud APIs enable automation for efficient extraction.

Exfiltration via Mobile Apps

Compromised smartphones can exfiltrate data through normal-looking mobile app activities like photo uploads or fitness tracking. The apps transfer data through the background to evade detection.

Exfiltration by Physical Medium

In some cases, hackers have exfiltrated data by writing it to physical media like USB drives, CDs or hardcopy papers and physically removing it from the premises. This leaves no digital traces.

How to Combat Data Exfiltration

While data exfiltration is an evolving threat, organizations can take steps to improve detection and prevention:

• Network traffic analysis – Inspect traffic patterns to uncover abnormal flows indicating potential exfiltration.

• Endpoint monitoring – Monitor processes and configurations on endpoints to detect misuse by insiders or compromised accounts.

• Data Loss Prevention – Implement a DLP solution to identify and block unauthorized attempts to exfiltrate sensitive data.

• Access controls – Limit access to sensitive data and systems to only those who require it.

• Education – Educate employees on data handling policies and how to spot potential data exfiltration.

• Incident response plan – Have an IR plan to rapidly detect and respond to potential exfiltration incidents.

Data exfiltration remains one of the top threats facing organizations today. As hackers develop new techniques, security teams must continuously adapt their strategies and tools to detect these sophisticated data breaches. Through vigilance and a defense-in-depth posture, companies can effectively mitigate the risks of stealthy data theft by malicious insiders or external threat actors.